Image forming apparatus, image forming method and computer-readable medium storing image forming program

1. An image forming apparatus, comprising: a tray configured to accommodate a sheet; an image forming device configured to form an image on the sheet; a data communication device; and a controller configured to: judge, when the data communication device receives first image data from an external device, whether a first sheet size corresponding to the first image data is larger than a size of the sheet accommodated in the tray; make first judgment, when the controller judges that the first sheet size is larger than the size of the sheet accommodated in the tray, whether the first image data has been generated by applying a resizing operation to original image data based on resize information which the data communication device receives from the external device, the resizing operation being an operation of trimming portions of an image to adjust an image size of the image data; make second judgment, when the first judgment judges that the first image data has been obtained by applying the resizing operation to the original image data, whether the resizing operation is to be applied to the first image data in order to make an image size of the first image data meet an in-use sheet size based on a portion of an image represented by the first image data which protrudes with respect to the in-use sheet size; resize the image size of the first image data to meet the in-use sheet size by applying the resizing operation to the first image data when the second judgment judges that the resizing operation is to be applied to the first image data; and control the image forming device to form an image on the sheet based on the first image data to which the resizing operation has been applied.

2. The image forming apparatus according to claim 1 , wherein, when the first judgment judges that the first image data is generated by applying the resizing operation to the original image data, and when resizing operation is applied to the first image data so as to make the image size of the first image data meet the in-use sheet size, the second judgment judges that: the resizing operation is to be applied to the first image data if the size of areas trimmed in the resizing operation is less than a predetermined ratio of the original image size of the original image data; and the resizing operation is not to be applied to the first image data if the size of the areas trimmed in the resizing operation is equal to or more than a predetermined ratio of the original image size of the original image data.

3. The image forming apparatus according to claim 1 , wherein, when the first judgment judges that the first image data is generated by applying the resizing operation to the original image data, and when resizing operation is applied to the first image data so as to make the image size of the first image data meet the in-use sheet size, the second judgment judges that: the resizing operation is to be applied to the first image data if areas to be trimmed in the resizing operation and areas having been trimmed from the original image and indicated by the resize information are on the same side; and the resizing operation is not to be applied to the first image data if areas to be trimmed in the resizing operation and areas having been trimmed from the original image and indicated by the resize information are not on the same side.

4. The image forming apparatus according to claim 1 , wherein: the resizing information indicates an image size of the original image corresponding to the first image data; and the first judgment judges whether the first image data has been generated by applying the resizing operation to the original image data based on comparison of the image size of the original image data indicated by the resize information with the image size of the first image data if the set sheet size is judged to be larger than the size of the in-use sheet.

5. The image forming apparatus according to claim 1 , wherein: the controller is configured to further transmit the size of the in-use sheet to the external device so that the external device that has transmitted the first image data applies the resizing operation to the original image data corresponding to the first image data based on the in-use sheet size when the second judgment judges that the resizing operation is not to be applied to the first image data; and when the size of the in-use sheet is transmitted, and when the data communication device receives the second image data which is generated by applying the resizing operation to the original image data based on the in-use sheet size the controller causes the image forming device to form an image on the sheet based on the second image data.

6. The image forming apparatus according to claim 5 , wherein, when the data communication device does not receive the second image data from the external device within a predetermined period after the in-use sheet size was transmitted to the external device, the controller modifies the first image data to reduce the image size of the first image data to a size smaller than the in-use sheet size and causes the image forming device to form the image based on the based on the modified first image data.

7. The image forming apparatus according to claim 1 , wherein, when the second judgment judges that the resizing operation is not to be applied to the first image data, the controller modifies the first image data to reduce the image size to a size equal to or smaller than the in-use sheet size and causes the image forming device to form the image on the sheet based on the modified first image data.

8. The image forming apparatus according to claim 1 , wherein, when the first judgment judges that the first image data is not generated by applying the resizing operation to the original image data, the controller applies the resizing operation to the first image data to make the image size of the first image data meet the in-use sheet size.

9. The image forming apparatus according to claim 1 , wherein: the controller is further configured to judge whether trimming designated by a user has been applied to the first image data based on trimming information which is received, from the external device, by the data communication device and indicates whether the trimming designated by the user has been applied to the first data when the set sheet size is larger than the in-use sheet size; and when it is judged that first image data is data to which trimming designated by the user has been applied, and when the data communication receives a margin printing setting from the external device, the second judgment judges that the resizing operation is to be applied to the first image data if a ratio of the amount of the margin, which would be formed if the resizing operation would be applied to the first image data so as to make the image size of the first image data meet the in-use sheet size, to a margin when the resizing operation would not be applied is not equal to or more than a predetermined amount; and the second judgment judges that the resizing operation is not to be applied to the first image data if a ratio of the amount of the margin, which would be formed if the resizing operation would be applied to the first image data so as to make the image size of the first image data meet the in-use sheet size, to a margin when the resizing operation would not be applied is more than the predetermined amount.

10. A non-transitory computer-readable recording medium storing instructions to be executed by a controller of an image forming apparatus, the image forming apparatus having a tray configured to accommodate a sheet, an image forming device configured to form an image on the sheet and a data communication device, the instructions, when executed, cause the controller to: judge, when the data communication device receives first image data from an external device, whether a first sheet size corresponding to the first image data is larger than a size of the sheet accommodated in the tray; make first judgment, when the controller judges that the first sheet size is larger than the size of the sheet accommodated in the tray, whether the first image data has been generated by applying a resizing operation to original image data based on resize information which the data communication device receives from the external device, the resizing operation being an operation of trimming portions of an image to adjust an image size of the image data; make second judgment, when the first judgment judges that the first image data has been obtained by applying the resizing operation to the original image data, whether the resizing operation is to be applied to the first image data in order to make an image size of the first image data meet an in-use sheet size based on a portion of an image represented by the first image data which protrudes with respect to the in-use sheet size; resize the image size of the first image data to meet the in-use sheet size by applying the resizing operation to the first image data when the second judgment judges that the resizing operation is to be applied to the first image data; and control the image forming device to form an image on the sheet based on the first image data to which the resizing operation has been applied.

11. An image forming method of an image forming apparatus having a tray configured to accommodate a sheet, an image forming device configured to form an image on the sheet and a data communication device, the method includes steps to: judge, when the data communication device receives first image data from an external device, whether a first sheet size corresponding to the first image data is larger than a size of the sheet accommodated in the tray; make first judgment, when the controller judges that the first sheet size is larger than the size of the sheet accommodated in the tray, whether the first image data has been generated by applying a resizing operation to original image data based on resize information which the data communication device receives from the external device, the resizing operation being an operation of trimming portions of an image to adjust an image size of the image data; make second judgment, when the first judgment judges that the first image data has been obtained by applying the resizing operation to the original image data, whether the resizing operation is to be applied to the first image data in order to make an image size of the first image data meet an in-use sheet size based on a portion of an image represented by the first image data which protrudes with respect to the in-use sheet size; resize the image size of the first image data to meet the in-use sheet size by applying the resizing operation to the first image data when the second judgment judges that the resizing operation is to be applied to the first image data; and control the image forming device to form an image on the sheet based on the first image data to which the resizing operation has been applied.